Study of the Role of Genetic Modifiers in Hemoglobinopathies

Hemoglobinopathies, including sickle cell disease (SCD) and beta-thalassemia, are prevalent diseases with variable clinical manifestation and severity that are thought to be governed, in part, by genetic modifiers. Despite the identification and characterization of a few putative genetic modifiers by previous studies, these are as yet insufficient to guide treatment recommendations or risk-stratify patients reliably. Also, it is expected that many additional genetic variants exist that can modify disease and its severity. This large-scale genome-wide association study (GWAS) will utilize SNP chips to investigate the genetic profile of individuals with hemoglobinopathies, thereby addressing the challenges of previous studies related to small sample sizes and low statistical power, while promoting the participation of diverse populations worldwide. The study aims to i) discover new genetic modifiers of hemoglobinopathies, ii) validate previously reported genetic modifiers, iii) pool and analyze existing genomic data, iv) standardize phenotypic descriptions, v) develop a research resource of disease-specific data generated in INHERENT, including genomic, phenotypic, and functional data, and vi) develop risk scores that can be used for patient stratification.

The main endpoints include:

1. Worldwide demography, including numbers of patients, main genotypes, and overall disease severity/burden in participating centres

2. Genetic modifiers affecting clinical or laboratory phenotypes of hemoglobinopathies, including

   1. overall survival in SCD and/or thalassemia,

   2. stroke and/or decreased neurocognitive function in SCD and/or thalassemia,

   3. renal impairment in SCD and/or thalassemia,

   4. leg ulcers in SCD,

   5. priapism in SCD,

   6. mild or severe acute pain and/or chronic pain syndromes in SCD,

   7. pulmonary hypertension in SCD and/or thalassemia,

   8. hyperhemolysis in SCD and/or thalassemia,

   9. fetal hemoglobin levels,

   10. degree of ineffective erythropoiesis,

   11. hepatic fibrosis/cirrhosis and/or cardiac siderosis,

3. Genetic modifiers affecting response to treatment, including

   1. response to hydroxyurea,

   2. response to iron chelation treatment,

   3. response to emerging therapeutic agents